very lethal

this is the 'wasp knife' or 'gas knife' now becoming popular. original invention was credited to nazi saidist himmler. hhhmmmmm. is someone forgetting the past?

Deadly Compressed Air Knife (Updated)By Sharon Weinberger If you were creeped out by the compressed air gun used by the villain in No Country for Old Men, you might want to skip this post. There's a new patent out for a deadly compressed gas knife, which like its name suggests, injects compressed air into the victim (making it a more deadly weapon than a regular knife).

The kife would be "particularly useful for a diver and that when an undersea creature is pierced, the compressed gas both causes tissue and organ damage and provides buoyancy to float the creature towards the surface."

Here's more from the patent:

The handle has an internal cavity containing a compressed gas source and the blade is affixed to the handle. The blade has an internal bore running along a longitudinal axis from the handle to a point proximate a tip. The blade further has an aperture extending from a first edge to the internal bore at an anglerelative to the longitudinal axis of between 15.degree. and 75.degree.. The trigger has a depressed position and a not depressed position. When in the depressed position, the internal bore communicates with the compressed gas source and when in said not depressed position, the internal bore is blocked from the compressed gas source. When a creature is pierced with the knife, the trigger is depressed injecting compressed gas into the creature greatly enhancing the incapacitating effect of the knife.

The knife is designed for scuba divers, not murderous lunatics, says the patent. Then again, the compressed air gun in No Country for Old Men was meant for cattle.

Update:

DANGER ROOM's very own David Hambling reminds me that the compressed air knife has a precursor, the Farallon Shark Dart, a U.S. Navy weapon from the 1970s:

The most common version resembles a slim dagger, with a CO2 cartridge in the handle and a long hollow needle for a blade. The idea was to stab the shark, causing the CO2 to be released into its body. The idea was that this would not kill it but would affect its buoyancy, forcing it to break off the attack without leaving much blood in the water. The reality may have been more gruesome.

"I saw some footage on it, it was horrible," says a diver describing the effects here. "Their bellies would inflate and they said it would force the shark’s stomach out of their mouths."